I don't think that's a charitable take of the article. To many programmers, it wouldn't be obvious that some of these footguns (autoboxing, string concatenation, etc) are "bad", or what the "good" alternatives are (primitives, StringBuilder, etc).
That said, the article does have the "LLM stank" on it, which is always offputting, but the content itself seems solid.
Of course it's not. I don't see any reason of posting an article that repeats the very same basics of Java or literally any programming language. Simple basics. Sure, if a particular programmer is not aware of these, the particular programmer would be very surprised that any of their operations are not imaginary O(0) (if they'd even care).
That said, the article does have the "LLM stank" on it, which is always offputting, but the content itself seems solid.